/Engine/Plugins/Interchange/Runtime/Source/Import/Public/MaterialX/MaterialXUtils/MaterialXBase.h
Convert math nodes (add, sub, div, mul) that have a neutral input, to the MaterialXnode which is simply the identity or a noop This allows us to optimize the final shader by avoiding unnecessary operation on a material (for example a*1 = a) This function should be called after the subgraphs substitution in order to search for all the nodes even in the subgraphs
static void ConvertNeutralNodesToDot ( MaterialX::ElementPtr NodeGraph )